What are suppositories?
solid, single dose preparations
they contain 1 or more active substances dispersed/dissolved in a suitable basis that may be soluble or dispersible in water and may melt at body temperature
types of suppositories
rectal
vaginal (pessaries)
rectal blood circulation
superior rectal artery - main blood supply
haemorrhoidal veins (superior, middle, inferior veins) - drug absorption
drug absorption from inferior/middle veins - bypass 1st pass metabolism
absorption from superior veins - liver, 1st pass metabolism
SYSTEMIC effects of rectal suppositories
analgesia - paracetamol/NSAIDs
CNS disorders - diazepam
infections - ampicillin
LOCAL effects of rectal suppositories
haemorrhoids
constipation
colitis
dosage forms used rectally
suppositories ointments enemas tablets soft capsules
advanages of vaginal route
high blood supply
avoidance of liver metabolism
disadvantages of vaginal route
low moisture content - affects disintegration of some dosage forms
pH varies - 3.5-4.5, hormonal stages (pregnancy, menopause)
local effects of vaginal route
infections - candida (thrush), trichomonas infections
local HRT
systemic effect of vaginal route
HRT - oestrogens, prostaglandins
dosage forms via vaginal route
suppositories/pessaries gels creams foam tablets
body temp and suppositories/pessaries
vehicles melt/soften at body temp
g of med in rectal/vaginal suppositories
rectal
vaginal
- 3-5g
ideal suppository base
types of suppository bases
advantages of oleaginous/fatty bases
disadvantages of oleaginous bases
cocoa-butter (Theobroma oil)
polymorphic forms of cocoa butter
alpha, beta’, beta, gamma
cocoa butter substitutes
composition of ondansetron suppositories (Zofran)
ondansetron 16mg
Witepsol S58 (cocoa butter substitute)
composition of Alvedon suppositories
paracetamol 60/125/250mg
Witepsol H12
advantages of hydrophilic bases
appropriate for lipophilic drugs
disadvantages of hydrophilic bases
hygroscopic (need to absorb rectal/vaginal fluids)
slow dissolution
mucosal irritation